|Moon Jelly (Aurelia aurita)|
This week we commemorate the 45th anniversary of the first moon landing (by Apollo 11 on July 20, 1969) with a photo of a Scyphozoan known as the Moon Jelly. Jellies of the genus Aurelia are common in coastal waters worldwide, including the Arctic.
In the photo you can see the four oral arms suspended from the body of the jelly, arranged around the critter's mouth. Along the edge of the bell of the Moon Jelly are tiny hair-like tentacles -- not really visible in this photo. Both the tentacles and the oral arms bear nematocysts, the stinging cells used for defense and to immobilize prey. Moon Jellies "prey" on zooplankton.
I photographed this Moon Jelly (A. aurita) in the Aegean Sea, just a few meters from the shore near Vouliagmeni, Greece. This one was about a foot (30 cm) in diameter, although some nearly half again as large have been recorded.